In case you still see lock timeouts after house keeping, please use the following scripts
https://github.com/stephan-volz/database-scripts
Depending on your database related skills, you can either
- review yourself and see if for example statistic updates are required,
which tables still hold a very high number of rows or how any snapshots you have.
- share this with IBM BPM Support to get further advise on how to reduce the amount of data.